#include<stdio.h> 
#include<string.h>

int main(int argc, char* argv[])
{
    if(argc != 2)
    {
        printf("Usage: %s -[a,b,c,d]\n", argv[0]);
        return -1;
    }
    if(strcmp(argv[1], "-a")==0)
    {
        printf("This is function 1\n");
    }
    else if(strcmp(argv[1], "-b")==0)
    {
        printf("This is function 2\n");
    }
    else if(strcmp(argv[1], "-c")==0)
    {
        printf("This is function 3\n");
    }
    else if(strcmp(argv[1], "-d")==0)
    {
        printf("This is function 4\n");
    }
    else
    {
        printf("Sorry, no this function\n");
    }
    return 0;
}
